Today's telephony networks are being employed to support many different communication devices using many different communication protocols. A typical office, for example, is equipped with electronic communication equipment, such as touch tone telephones, facsimile machines, and modems for Internet communications. The office communication equipment communicates with a device at a central office, for example, which, in turn, facilitates communications between the office communication equipment and a node located elsewhere on a POTS (Plain Old Telephone System) network, the Internet, or other electronic network. Service providers maintain, upgrade, and profit from the communication services provided by the central office communication equipment.
Service providers are limited in the amount of space available where the equipment is located, which is typically a central office. Increasing the number of voice line channels capable of being supported by a media gateway is important to service providers because service providers generate revenue as a function of the number of voice channels that can be supported by their equipment.
A device at the central office that is used to provide communication services for the office communication equipment is known as the media gateway. Among several services provided, the media gateway connects the office communication equipment on the POTS network to another network, such as the Internet.
Another service provided by the media gateway is encoding voice signals into voice-over-IP (VOIP) packets, where IP means Internet Protocol. Yet another service provided by the media gateway is detection of the several communication protocols used by the office communication equipment.
A digital signal processor is a device in the media gateway that processes communication signals carried by the voice channels. Digital Signal Processors (DSP's) are sophisticated computer chips that efficiently execute many low-level mathematical processing functions. For instance, addition and multiplication functions are executed in parallel to perform both functions in one clock cycle, thereby increasing the processing speed (i.e., throughput) of voice channel communication signals. By increasing the processing speed, many voice channels can be serviced by a single DSP and, therefore, less physical space is occupied by equipment capable of supporting more channels.
The DSP is also capable of executing high-level functions, such as signal classification, in which a signal classifier distinguishes communication protocols from one another. The classifier detects sinusoidal signals (sinusoids) composing the several communication protocols during the dialing portion of the communication protocols. For example, the dual-tone of dialed digits from a touch tone telephone (i.e., DTMF—Dual Tone Multiple Frequency) have sinusoids of different frequencies from those of other protocols (e.g., MF-R1—Multiple Frequency, One Row, a digital protocol used between digital networking devices).
Classifiers are traditionally processing intensive, time consuming techniques when executed in software on a signal processor, using several (e.g., five) MIPS (Million Instructions Per Second) or more to classify signals. Since DSP's are generally only capable of two hundred MIPS, the DSP's can only support a few classifiers since many more functions and general overhead processes are required to be done by the DSP. Thus, the media gateways must employ many DSP's to support the high numbers of customers using digital telephony equipment. The number of customers are expected to increase as other telephony services, such as VOIP, become more widely used.